body, html {
  background-color: white;
  height: 100%;
  margin: 0;
}
#app {
  display: flex;
    flex-direction: column;
    height: 100%;
  background-color: #219331;
}
button{
  flex: 1;
  margin: 1rem;
  font-size: xx-large;
  font-family: Helvetica, sans-serif;
}